A northern New York state court has arraigned a prison worker accused of helping two convicted killers escape from U.S. prison near the Canadian border.

Fifty-one-year-old Joyce Mitchell pleaded not guilty Friday night in Plattsburgh to charges of promoting prison contraband — a felony that carries a sentence of up to seven years — and criminal facilitation, a misdemeanor that carries a one-year sentence. Her next court appearance is scheduled for Monday.

She is accused of befriending Richard Matt, 48, and David Sweat, 34, at the Clinton Correctional Facility in Dannemora, New York, and of smuggling contraband in to them.

District Attorney Andrew Wylie told reporters Friday that his office is considering other charges.

Wylie said that Mitchell, who worked as a supervisor in the prison tailor shop, had been cooperating with his office and revealing more about the breakout last Friday night or Saturday morning.

Earlier, Wylie told reporters that Mitchell did not bring power tools into the prison, although he did say she smuggled in “some form of equipment or tools.” CNN has quoted investigators as saying that Mitchell smuggled in hacksaw blades, two pairs of eyeglasses with lights affixed to them and drill bits.

Matt and Sweat used power tools to cut through the back of their cell wall and through steel pipes as they made their escape. The prison has power tools in its inventory but these have been said to be accounted for.

Wylie said that in the past year, Mitchell had been investigated for having an improper relationship with Sweat. Wylie said the investigation did not turn up enough to warrant disciplinary action but Mitchell was separated from one or both of the prisoners for a period of time.

Mitchell’s family has said she would not help prisoners escape.

The search

A huge manhunt continued for the escaped pair, much of it centered only a few kilometers from the prison. Rain hampered searchers on Friday.

“You’ve got to assume they are cold, wet, tired and hungry,” regional State Police Commander Major Charles Guess said, “but I would remind the community, the residents, that that makes these individuals even more dangerous and desperate.”

Guess said the search is continuing in the vicinity of the prison because “there is no conclusive evidence that either of the inmates has left the area.” He added that police are maintaining a high profile in the area because of “a very concerned population.”

Three hundred new searchers were added to the local, state and federal law enforcement personnel who were hunting for the fugitives, bringing the total to 800. Authorities say the additional personnel are needed to give the searchers adequate rest.

Authorities have received more than 700 leads in the case.

Previously, the longest escape from a New York prison was three days.

Sweat is serving a life sentence for the 2002 death of a sheriff's deputy. Matt is facing 25 years to life in prison on murder, kidnapping and robbery charges following the 1997 killing of a man.